Congenital anomalies of the urogenital tract (UGT) represent the third most frequent of all birth defects, occurring in approximately 26-30/10,000 live births. Only heart and limb defects are more prevalent. Such defects can vary from severe (persistent cloaca, cystic kidney disease, hydronephrosis, diphallia) to more moderate (hypospadias, streak gonads, horseshoe kidney, micropenis, crytorchidism, unilateral renal agenesis). Some cancers of the urogenital tract (gonadoblastoma, Wilms' tumour) represent a persistence of the embryonic state. In addition, adult onset renal disease and other disorders of the UGT show reactivation of molecules key to the normal development of the UGT. Indeed, there is now evidence that the number of nephrons endowed before birth in your kidneys can affect whether or not you will present with chronic renal disease later in life. All these observations highlight the need to comprehensively understand the molecular basis of UGT development. The starting point for this understanding is the temporal and spatial analysis of all genes expressed during UGT development. Genomic tools such as library construction and microarray- based expression profiling produce datasets that are not readily interpretable in terms of function without a cellular context. Hence, expression data needs to be communally collected as in situ data and amassed in a visual atlas. As part of our current funding from the NIDDK, we have generated (and will continue to do so) expression profilng data from across time and space in the developing kidney and ureter. Hence we have defined a set of approximately 2500 genes tht we know are involved in UGT development. Our current focus is only on secreted and transmembrane encoding genes. We propose to comprehensively analyse the expression of these genes in the developing UGT using wholemount in situ hybridisation (ISH) of E9 whole embryo, E10.5-13.5 UGT and section ISH of E15.5, 17,5 and adult kidney, testis, ovary, ureter and bladder. Section ISH will be performed using a Tecan Freedom EVO 150 Genepaint system. Immunohistochemistry for known renal subcompartment markers will be performed after ISH to clarify the localisation of the expression. The genes which we will analyse will come from our own microarray-based expression profiling of kidney development over time and within subcompartments (dynamic and spatially-restricted), or meta- analysis of other datasets, including the RIKEN data on kidney expression and microarray-based expression 3rofiling of normal kidney or renal disease.